Forging apparatus and stock warming means therefor



Aug. 25, 1959 P. w. KLOOZ 2,901,583

FORGING APPARATUS AND STOCK WARMING MEANS THEREFOR Filed Aug. 1'7, 1956 2 Sheets- Sheet 1 INVENTOR B404 M14002 ATTORNEYS P. W. KLOOZ Aug. 25, 1959 FORGING APPARATUS AND s'rocx WARMING MEANS THEREFOR Filed Aug. 17, 1 956 2 Sheets-Sheet 2 INVENTOR fibuahKfiZaoZ mNK h ..n 3.. 0. NW w. E

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United States Patent FORGING APPARATUS AND STOCK WARMING MEANS THEREFOR Paul W. Klooz, West Hartford, Conn, assignor to The Holo-Kronre Screw Corporation, Hartford, Conn., a corporation of Connecticut Application August 17, 1956, Serial No. 604,758

9 Claims. (Cl. 219-10.49)

This invention relates to metal forming and more specifically to an improved method and apparatus for heat treating metal wire and rod stock immediately prior to the forming operations.

Inthe fabrication of metal parts such as screws, bolts, rivets, pins and the like, steel or other alloy in the form of wire or red is fed to forming apparatus frequently referred to as a header. The wire or rod is severed into predetermined lengths and the header forges each severed length of rod or wire to provide an article of a desired shape and configuration. In the case of a bolt or screw, the articles would be provided with an elongated shank and an enlarged head of the desired outer contour which may include slots or depressions. The heading operation according to known processes is performed in several stages and with cold forging processes it has been necessary to perform the heading operation in three or more steps with the partially formed blanks being annealed between each step to relieve stresses and strains and soften the material for the next operation. Annealing of the blanks between forging operations has also been found necessary in order to prevent fracturing of the material and obtain even reasonable life from the forging dies.

In some cases a so-called progressive method of forging or heading is employed which provides for the completion of heading operation in as many as four or five gradual steps. This procedure however not only involves considerable added expense. in the provision of the relatively large member of dies and punches and a relatively complicated machine for automatically performing many heading operations, but the. rate of production is low and the quality of the resultant product is below acceptable standards.

It has been found that with. the present invention the difliculties encountered with prior methods of forging articles from metal rod and wire are substantially completely overcome with the result that high quality articles can be fabricated at a more rapid rate and at the same time the life, of the dies as compared with prior methods is greatly extended.

Another object of the invention resides in the provision of an improved method and apparatus for treating the metal rod and wire stock immediately prior to the heading operation and at the same time accurately coordinating the treatment with the characteristics of the heading operation so. that the severed piece being formed by the header will attain an optimum forming temperature. This is accomplished through the coordination of the temperature changes in the metal blanks during the heading operation with the heat imparted to the rod or wire just prior to the heading operation in such a manner that the temperature attained by the formed blank during the heading operation will be maintained within a range that will prevent fracturing or rupturing of the metal. At the same time the blank is maintained in a warmed state that will enable. the heading or forming to be accomplished in materially fewer steps than has heretofore been required. In most cases it has been found that a so-called two-blow header for performing the heading operation in two steps can be used to produce high quality metal articles and at the same time provide long die life and a higher rate of production.

Another object of the invention resides in the provision of novel and improved warming or heating means for wire and rod stock that will provide a substantially fool-proof and dependable device for maintaining the temperature attained by the blank during the heading operation within predetermined limits.

A still further object of the invention resides in a novel and improved method for heat treating wire and rod stock preparatory to the forging of articles therefrom.

A still further object of the invention resides in improved heating apparatus for rod stock having means for selectively heating discrete portions of the stock particularly in instances wherein the stock is provided with an intermittent feed. It has been found that by producing predetermined temperature gradients in the stock and coordinating these gradients with the lengths of stock to be severed for the forming operation it is possible to provide accurate control over the resultant maximum temperature attained by the metal during the actual heading operation. In this way the heading operation can be performed more quickly and easily and at materially reduced costs.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the steps, construction, combination of elements, process and arrangement of parts which will be exemplified in the construction and process hereafter set forth and the scope of the application ofwhich will be indicated in the appended claims.

In the drawings:

Fig. l isafragmentary and partially diagrammatic plan view of heading or forging apparatus embodying the invention;

Big. 2 is a cross sectional view of the warming apparatusofFig. 1 takenalong the line -2--2 thereof;

Fig; 3 he cross sectional view taken along-the line 3-3 of Fig. 2;

Fig. 4'isv a. side view of the conductors and the supporting means therefor supplying an electrical energy to the heatingmeans andtaken in the direction ofthe arrow -4iof.Fig. 1;

Fig. 5 is a cross sectional view of'Fig. 4 taken along the line 5-5 thereof;

This application constitutes a continuation in part of US. patent application, Serial No. 515,709 filed June 15, 1955 entitled Method and Apparatus for Cold Forging.

The invention more specifically concerns the provision of improved method and apparatus for warming or heating metal wire and rod stock immediately prior to the severance of the stock into pieces of predetermined length to be forged by heading apparatus. The heating means is v arranged and coordinated with the 'stock severing means and headingapparatus so that each piece or blank will attain a predeterminedtemperature upon severance and immediately prior to the heading operation. The control of the temperature in-this way is accomplished by improved apparatuszpreferably embodying a high frequency heating coil spaced a distance from the heading apparatus governed by the length. of the pieces to be severed and coordinated relative to the severing means so that the temperature of each length of stock just prior to severance will lie within predetermined limits. The control of the temperatureis accomplished. by an improved heating unit and transfer means for guiding the heated rod to the heading apparatus.

Referring now to Fig. 1 there is illustrated diagrammatically a forming machine including the forming apparatus generally denoted by the numeral 10, rod or wire cut 011 means 11, a pair of feed rollers 13 and 14 for feeding a rod or wire 15 to the cutter 11 and forming apparatus 10, heating means 16 disposed between the rollers 13 and 14 and the cutter 11 and means in the form of a quill 17 for guiding the heated rod from the heater 16 to the cutter 11. The heating means 16 includes a coil preferably of copper tubing or the like energized by high frequency generating means 18 through a pair of insulated conductors 19 and 20.

The forming apparatus may be of any suitable construction, as for example, the apparatus shown in a prior patent to Purtell No. 2,236,733 issued in 1941.

In the illustrated embodiment of the invention the driving or feed rolls 13 and 14 are supported by the frame 21 and powered by suitable intermittent drive means 22. The heating means 16 is disposed between the feed rolls 13 and 14 and the cutter 11 and is preferably coordinated with the cutter 11 so that heat is applied substantially uniformly to successive discrete portions of the stock that ultimately form independent pieces or blanks upon severance by the cutter 11. The stock 15 upon being heated is fed to the cutter 11 by the guide or quill 17 which shields the heated stock to restrict heat dissipation and is arranged with relatively narrow supporting surfaces to reduce the loss of heat through direct conduction to the machine frame.

The heating means 16 and the guiding means 17 are illustrated more clearly in Figs. 2 and 3 of the drawings. With reference to the heating means 16, it includes an elongated housing 23 of generally rectangular configuration and has a pair of aligned openings 24 and 25 through which the stock 15 passes. The opening 24 includes a bushing or die 26 adapted to slidably accommodate the particular size of wire or rod being used to fabricate the finished articles. This die may be held within the opening 24 by a set screw 27 or other suitable means. In order to obtain a more dependable and reliable feed for the rod 15 the housing 23 is tapered as indicated at 28 and 29 to conform roughly with the radii of the feed rolls 13 and 14. The outer end of the die 26 is also tapered so that the distance between the point of contact of the stock 15 with the feed rollers and the face of the die 26 can be maintained as short as possible.

The opening 25 in the housing 23 is arranged to accommodate an elongated bushing 30, the latter having a section 31 of reduced diameter and a tapered portion 32 for reception by the housing 23 to limit the innermost position of bushing with reference to the housing. The bushing 30 is held in the housing 23 by a set screw 33 or other suitable means. The central opening 30' within the bushing 30 is aligned with the opening 26 in the bushing 26 to avoid unnecessary deflection of the stock 15 in its passage through the housing 23.

The quill or guide 17 is supported by the frame member 34 in any suitable manner and is provided with a plu rality of outwardly extending circumferential ridges 35 by which it is mounted in poor thermal contact with frame 34 and quill 17 is provided with a smooth interior to accommodate the particular size of stock being fed to the header 10. The quill 17 is preferably formed of a material having relatively low heat conductivity such as stainless steel or the like. In order to align accurately the opening 30' of the bushing 30 with the opening in the quill 17 the frame 34 is arranged to receive the right hand end of the bushing 30 as illustrated in Fig. 2 and the bushing is locked in the frame member 34 by means of a set screw 36.

Referring again to the heating means 16 and more specifically the housing 23, the latter is provided with a recess 37 disposed between and in elfect intercepting the openings 24 and 25. The recess 37 is formed in both the front and bottom walls 38 and 39 respectively of the block or housing 23 and extends beyond the openings 24 and 25 to leave a narrow downwardly extending rear wall portion 40 and a narrow bottom flange 41 originally constituting part of the bottom wall 39. The upper portion 42 of the recess 37 is somewhat shallower than the lower portion 43. As will be shown, the recessed part 43 is arranged to ac commodate the heating element while the recessed part 42 accommodates means for holding the heating element within the recess 43.

While the actual heating means may take any desired form, in the illustrated embodiment of the invention, it is in the form of a helical tube 44 with the ends 45 and 46 being connected with the hollow conductors 20 and 19, respectively. Although the coil is illustrated in an uncoated form, it may include a coating of a relatively rigid heat resistant, electrically insulating material such as a ceramic coating, to afford additional mechanical and electrical protection. The D.-C. resistance of the coil 44 is substantially zero and it is fed by high frequency energy. Accordingly the number and diameter of the turns forming the coil must be accurately coordinated with the frequency of the generator 18 so that the coil, with the stock 15 extending therethrough, will present the desired inductance to the generator 18 in order that the generator may impart power to the coil.

It is preferable to coordinate the position of the coil 44 with reference to the cutter 11 so that a predetermined temperature can be produced within the rod 15. For this purpose the recess 43 is made slightly longer than the coil 44 so that the latter can be moved longitudinally thereof. An improved support adjustably holds the coil within the recess and in alignment with the openings in the bushing 26 and 30. Through an improved arrangement of elements, the coil support affords air cooling for the coil, reduces heat conduction to the housing 23 and facilitates removal of the coil from the housing or block 23 for repair or replacement.

The inner coil support is in the form of an elongated plate 47 of heat resistant insulating material that rests firmly against the back wall 40 of the recess 43 and is held in place by the lip or flange 41. The exposed side of the plate 47 is provided with a cylindrical concave recess 48 for receiving the inner side of the coil 44. A second plate 49 of insulating material also has a cylindrical concave recess 50 for engaging the outside of the coil 44 as illustrated in Fig. 3. The two plates 47 and 49 together with the coil 44 supported therebetween are held in the recess by an outer bracket member generally denoted by the numeral 51. The upper portion 52 of this bracket member, also formed of insulating material, is generally rectangular in section and is adapted to be received within the recess part 42. The lower portion of the bracket member 51 is in the form of a depending skirt 53 having an inwardly formed flange 54 on the bottom thereof to engage and hold the plate 49. The bracket member 51 is secured to the housing 23 by a pair of cap screws 55 extending through the bracket part 52 and threadably received in cooperating openings in the housing 23. With this arrangement the coil 44 can be displaced longitudinally within the recess 43 and the cylindrical concave recesses in the plates 47 and 49 will hold all of the turns of the coil 44 in precise alignment with the openings in the bushings 26 and 30. Moreover by supporting the coil in this way an air space is provided above and below the coil so that the coil is not only rigidly supported at all times but maximum ventilation is provided for cooling. In supporting the coil 44 within the recess 43 it is desirable to provide, in addition to the required electrical insulation, heat insulation to prevent the direct conduction of heat into the housing or block 23. While any suitable insulating material may be utilized for this purpose, it is preferable to form the plates 47 and 49 together with the bracket member 51 of a rigid insulating material comprising asbestos and a suitable binder. A material of this character is presently manufactured under the trade name Transite.

The supporting means for the conductors Band 20, connecting thehigh frequency generator 18 with the coil 44, is shown in Figs. 4 and 5. This supporting means is in the form of a pair of plates 56 and 57 separated by a layer of insulating material 58 of Transite or the like. The conductor 20 is welded or otherwise suitably secured to the plate 56 while the conductor 19 is similarly attached to the plate 5 7. The plates 56 and 57 together with the intervening insulating material 58 are secured one to the other by means of a plurality of connectors generally denoted by the numeral 59. Each connector includes a central bolt 60, a centering washer 61 for engaging a cooperating opening 62 in the plate 57 and a second centering washer 63 for engaging the cooperating opening 64 in the plate 56. The insulating material 58 is drilled to receive the bolt 60 which secures the assembly together. With the foregoing arrangement the plates 56 and 57 are electrically coupled to the conductors 19 and 20 and are insulated one from the other. Thus the plates form a condenser in parallel with the coil and form part of the resonant circuit which includes the heating coil.

It has been found that in order to control the precise temperature of the rod 15 and to insure the attainment of a predetermined temperature of each severed piece, it is important to prevent the accumulation of heat in the housing 23 and to transfer the heated wire or rod stock to the cutter 11 as rapidly as possible to minimize the loss of heat through radiation and conduction. For this purpose a suitable coolant is circulated through the con ductors 19 and 20 to cool the coil 44 and a portion is diverted through a passage 65 inthe housing 23. Diversion of a part of the coolant is accomplished by the use of a pair, of T-connectors 66 and 67 inserted in scrim with the conductors 19 and 20. The T-connector 66 is connected toone end of the passage 65 by means of conduits 67" and 68 and an intervening conduit 69 of insulating material. The T-connector 67 is similarly coupled to the other end of the passage 65 by conduits 70 and71 and an intervening conduit 72 of insulating material. The circulation ofjthe coolant through the passage 65 maintains the housing 23 at the desired temperature and with intermittent forward motion of the stock 15 in the direction of the arrows as shown in Fig. 2, little or no heat will be imparted to the stock before the actual heating operation. In this way a predetermined temperature can be maintained in the stock 15 as it passes through the bushing 30. In order to effect the desired cooling of block 23, it is preferable to form it of aluminum, copper or other suitable material having a relative- 1y high rate of heat conduction.

In order to minimize the loss of heat in the rod or stock 15 after leaving the coil 44, the quill 17 previously described is preferably formed of stainless steel or other similar material having relatively low heat conductivity. It is also desirable to provide supporting ridges 35 which may be integral with the quill 17 and formed of stainless steel or other metal having a relatively low heat conductivity. In addition the coil 44 is placed relatively close to the cutter 11 so that in the normal operation of the machine each successive portion of the stock 15 arrives at the cutter 11 within a few seconds, at most, after leaving the. coil 44.

With the invention as described above and with a two blow header 10, the stock is preferably heated to a temperature of at least 150 to 200 degrees. This temperature is accurately controlled and the successive portions of the stock 16 will arrive at the cutter at approximately the same temperature. By reason of this relatively small amount of heat imparted to the stock 15, the temperature of the severed blanks upon being worked by the header will rise to about 450 to 650 degrees Fahrenheit. It is preferable, however, to adjust the temperature imparted by coil 44 to the particular type of stock bemg Worked so that the resultant temperature of the articles will be in the vicinity of 500 to 600 degrees, andnot exceeding 650 degrees Fahrenheit. This temperature has been generally found to be most desirable when working steel and other similar alloys, though the preferred temperature range may vary for dilferent alloys. The resultant temperature of the articles being formed directly depends upon the heat applied to the article immediately prior to the forming operation, and, after the elements of the machine have attained normal operating temperature, a temperature of 500 to 600 degrees in the finished articles will be automatically maintained. By controlling the temperature of the stock being formed in this way the material is maintained in a condition that will greatly facilitate forging by the headers with the result that exceedingly long die and punch life are obtained. At the same time critical temperatures of the stock are not exceeded and fractures or ruptures of the material are completely avoided.

In certain instances the entire heading or forming operation may be carried out in a single step. In this case it is desirable to preheat the stock 15 to a temperature of 250 to 400 degrees Fahrenheit depending on the nature of the heading operation. This temperature is adjusted to provide a resultant temperature in the forged article in the range of 500 to 600 degrees Fahrenheit as in the case with the two stage operation.

While only one embodiment of the invention has been illustrated and described, it is apparent that modifications, alterations and changes may be made Without departing from the true scope and spirit thereof.

What is claimed is:

1. Apparatus for warming wire and rod stock comprising an elongated cooled block of energy absorbing material including an opening extending therethrough for slidably receiving said stock, said block further including a central recess formed in one wall with a length less than said block, said recess intercepting a portion of the length of said opening, an induction heating coil within said recess formed of a plurality of spaced turns of an electrically conductivematerial, a plate of insulating material within said recess and having a shallow concavity therein for partially receiving one side of said coil, a second plate of insulating material having a concavity therein for at least partially receiving the opposing surface of said coil, and means for holding said plate of insulating material and said coil within said recess with the axis of the coil substantially coincident with the axis of said opening.

2. Apparatus according to claim 1 wherein said coil is coated with relatively rigid, heat-resistant, electricallyinsulating material.

3. Apparatus for warming wire and rod stock comprising a generally rectangular cooled metal block having a longitudinal opening extending therethrough for slidably receiving the stock to be warmed, said block further including an elongated recess therein encompassing at least part of two adjoining surfaces of said block and intercepting an intermediate portion of said opening to form a pair of spaced aligned stock-guiding openings, a helical induction heating coil within said recess, an insulating plate of heat resistant material in said recess having a concavity in one surface thereof for at least partially receiving said heating coil, a second insulating plate of heat resistant material having a concavity on one side thereof for at least partially receiving the other side of said coil, and insulating means secured to said block and engaging at least one of said insulating plates for securing both plates and said coil within the recess with the axis of said coil in substantial alignment with the axis of the aligned openings.

4. Apparatus according to claim 3 wherein said metal block includes means for circulation of a coolant there through and stock guiding and aligning bushings are carried by said aligned openings extending from each end of said recess.

5. Apparatus according to claim 3 wherein said insulating plates and said insulating means are formed of a rigid electric and heat insulating material containing asbestos and a binder.

6. Apparatus for warming wire and rod stock comprising a generally rectangular metal block having a longitudinal opening extending therethrough for slidably receiving the stock to be warmed, said block further including an elongated recess therein encompassing at least part of two adjoining surfaces of said block and intercepting an intermediate portion of said opening to form a pair of aligned openings, a helical heating coil within said recess, an insulating plate of heat resistant material in said recess having a concavity in one surface thereof for at least partially receiving said heating coil, a second insulating plate of heat resistant material having a concavity on one side thereof for at least partially receiving the other side of said coil, insulating means secured to said block and engaging at least one of said insulating plates for securing both plates and said coil within the recess with the axis of said coil in substantial alignment with the axis of the aligned openings, an elongated tubular stock guide extending from said block and in the direction of the stock feed, said guide having a plurality of spaced narrow ribs and guide supporting means engaging said ribs.

7. In apparatus for Warming wire and rod stock having spaced stock feeding and cutoff means, stock heating and guiding means between said feeding and cutoff means comprising induction heating means surrounding said stock, a shield at least partially surrounding said heating means restricting the flow of air about the last said means and formed of material absorbing electrical energy emitted by said heating means and heat radiation, means on said shield for removing heat generated therein to minimize heat radiation from said shield to said stock and stock guiding means surrounding said warmed stock and extending from said shield to raid cutoff means, said stock guiding means being formed of a low heat conductivity material.

8. In apparatus for warming wire and rod stock having spaced stock feeding and cutoff means, said apparatus further including induction heating means surrounding said stock between the feeding and cutoff means, a shield of energy absorbing material about said heating means and including cooling means restricting radiation of heat from said shield to said stock, and second shielding means of low heat conductivity material between the first said shield and said cutoff means, said shielding means minimizing air circulation about said stock and heating means and reciprocal temperature influences of said apparatus and stock one on the other.

9. In apparatus for warming wire and rod stock having spaced stock feeding and cutoff means, stock heating and guiding means between said feeding and cutoff means comprising induction heating means surrounding said stock, a shield at least partially surrounding said heating means restricting the flow of air about the last said means and formed of material absorbing electrical energy emitted by said heating means and heat radiations, means on said shield for removing heat generated therein to minimize heat radiation from said shield to said stock and stock guiding means surrounding said warmed stock and extending from said shield to said cutoff means, said stock guiding means being formed of a low heat conductivity material and having an elongated, tubular configuration with a plurality of spaced ribs on the outer surface thereof, said ribs forming the support for said tubular member in said apparatus to limit the transfer of heat 'between said stock guiding means and said apparatus.

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